Short-term tools to measure responsiveness to growth hormone replacement

Growth hormone (GH) replacement is a prolonged and expensive treatment modality which involves daily subcutaneous injections in children and adults. Efforts have been made, therefore, to develop short-term tests to predict long-term clinical response. The so-called insulin-like growth factor I (IGF-I) generation test was originally introduced in order to select responders to GH among short children without classical GH deficiency. A positive correlation between short-term increase in serum IGF-I and linear growth has, however, only been reported in a minority of studies. There is no single outcome measure available in GH-deficient adults, and no evidence of a correlation between IGF-I and the effects of GH replacement on factors such as body composition or physical fitness. In conclusion, no reliable short-term test to predict long-term response to GH replacement is available in either children or adults. For safety reasons, however, measurement of serum IGF-I concentrations in GH-deficient patients remains an important means of monitoring during GH replacement.